Why iodized salt still matters: the hidden iodine gap affecting health and brain development

Americans are now getting less iodine than they once did, and that trend may have consequences for children’s brains. According to Science News reporter Aimee Cunningham, iodine inadequacy nearly doubled from 2001–2002 to 2017–2018. In that later period, 24 percent of women and 30 percent of men age 14 and older were not getting enough iodine, and almost half of pregnant women fell short.

That matters because the body relies on iodine to produce thyroid hormones, which are crucial for fetal development and early brain growth. “Iodine deficiency is the leading cause worldwide of preventable developmental delay,” said Monica Serrano-Gonzalez, a pediatric endocrinologist at Hasbro Children’s and Brown University’s Warren Alpert Medical School.

The United States has dealt with this problem before. In the early 1920s, nearly half of schoolchildren in parts of Michigan had goiters. Iodized salt appeared in Michigan stores in 1924, Morton Salt introduced it nationally that fall, and by the 1950s goiter rates had fallen sharply. A study in the Journal of the European Economic Association found that men born in iodine-deficient regions later performed significantly better on a World War II Air Force qualifying exam after iodization became widespread.

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These days, grocery shelves are filled with Himalayan, kosher and sea salts. Only about 53 percent of table salt sold in U.S. stores is iodized, and many processed foods — a major source of salt in the American diet — typically use noniodized salt. “Iodized salt is important, but it may not be reaching everybody anymore,” said Elizabeth Pearce, an endocrinologist at Boston University Chobanian & Avedisian School of Medicine.

The government has never required iodization, and the CDC’s 2026 Nutrition Report says women of reproductive age in the U.S. are close to mild iodine deficiency. The American Thyroid Association and the American Academy of Pediatrics recommend a daily 150-microgram iodine supplement for anyone who is pregnant, breastfeeding, or planning a pregnancy.

The consequences can be serious. After a conflict in 1998 cut Ethiopia off from iodized salt, rural children experienced higher mortality and lower national exam scores, according to a 2026 study published in Nature Food.